1. Field of the Invention
The invention relates to antimicrobial agents, products incorporating such agents, and methods of making such products. More particularly, the invention relates to an antimicrobial agent suitable for impregnating and/or coating paper products and for coating certain medical devices.
2. State of the Art
In October 2001, several prominent Americans received letters containing the bacteria anthrax. Since then, the U.S. Postal Service has taken many steps to prevent the spread of deadly disease via the mails. Although all of the contaminated letters consisted of paper envelopes containing paper notes with anthrax powder, it has yet to be proposed that paper be manufactured with antimicrobial agents as a means for preventing the spread of disease via the mails.
A survey of the relevant art reveals that antimicrobial agents have previously been incorporated into various products for various reasons. For example, U.S. Pat. No. 3,864,468 to Hyman et al, issued Feb. 4, 1975, discloses non-porous polymeric articles having an active agent applied to the surface. The active agents include antibacterial and antifungal agents as well as insecticides, etc. The articles disclosed include polymeric films and fabrics as well as laminated products including polymeric films.
U.S. Pat. No. 4,282,366 to Eudy, issued Aug. 4, 1981, discloses organosilicon quaternary ammonium antimicrobial compounds which are allegedly suitable for impregnating cellulose fabrics to inhibit the growth of disease causing microorganisms. The single example illustrates the treatment of Whatman No. 1 filter paper. Mixed results were observed over a period of days with the best results from higher concentrations of the active agent.
U.S. Pat. No. 4,343,853 to Morrison, issued Aug. 10, 1982, discloses an antimicrobial treated fabric construction. The brief disclosure mentions a test involving a sweatshirt but no quantitative data is provided to measure the efficacy of the treated fabric construction.
U.S. Pat. No. 4,411,928 to Baldwin, issued Oct. 25, 1983, discloses a process for applying a microbiocidal finish to a fabric product such as a surgeon's gown, medical drape, isolation gown, instrument wraps, and the like. The disclosed microbiocidal agent is a silicone quaternary amine. The fabric produced is stated to have a bacteriocidal effectiveness of more than 95% in one hour. However, no experimental data is provided to substantiate the claim of effectiveness.
U.S. Pat. No. 4,533,435 to Intilli, issued Aug. 6, 1985, discloses an antimicrobial additive incorporated into the binding agent of a heavy-duty, kraft-type paper having the characteristics of substantial density, air impermeability, and improved printability. The antimicrobial additives disclosed consist of halogenated aromatic nitriles; a salt of imazalil sulphate; 3,5,3′,4′-tetrachlorosalicylanilide; and dichlorophene. The paper is intended for packaging surgical instruments or other sterile materials. It is stated that the antimicrobial additive migrates from within the binding agent onto the paper fibers to substantially eliminate the growth of micro-organisms thereon. However, no experimental data is provided to substantiate the claim of effectiveness.
U.S. Pat. No. 4,866,192 to Plueddemann et al., issued Sep. 12, 1989, discloses organosilicon quaternary ammonium antimicrobial compounds, particularly ammonium chloride derivatives of multifunctional diamino quaternary salts, and salts containing a combination of amino, ester, and fluoroalkyl, functionality. The compounds are not stated to be particularly useful for any specific application, although treatment of rayon cloth and use in moist towelettes is mentioned. When tested on rayon, results were mixed with higher concentrations yielding better results.
U.S. Pat. No. 5,026,723 to Katayama et al., issued Jun. 25, 1991, discloses a microbicidal/microbistatic synergistic composition for industrial use comprising a specific nitrobromopropane derivative and 4,5-dichloro-1,2-dithiol-3-one and an industrial method of killing or inhibiting the growth of microorganisms using the same compounds, which are useful of microbicidal/microbistatic treatment in various industrial media such as water used in making paper, industrial cooling water and the like.
U.S. Pat. No. 5,064,613 to Higgs et al., issued Nov. 12, 1991, discloses a method of treating surfaces in order to eliminate microbial growth by adding an antibacterially effective amount of an organosilicon quaternary ammonium silatrane compound to the surface in order to destroy bacteria and fungi. The compounds were tested on cotton and polyester yielding mixed results with higher concentrations performing better than lower concentrations.
U.S. Pat. No. 5,709,870 to Yoshimura et al., issued Jan. 20, 1998, discloses a silver-containing antimicrobial agent which is said to be excellent in affinity to fiber, antimicrobial property, antifungus property and stability to heat and light. It comprises carboxymethyl cellulose containing silver in the amount of 0.01 to 1% by weight and having the degree of substitution to carboxymethyl group of not less than 0.4. The carboxymethyl cellulose may be a crosslinked compound to make the antimicrobial agent water resistant. The antimicrobial agent is said to be well suited for application to paper, leather and porous material. According to the test results reported, the sterilization ratio of the compounds was at best 86% and in most cases less than 70%.
U.S. Pat. No. 5,869,172 to Caldwell, issued Feb. 9, 1999, discloses a variety of internally coated webs. The disclosure includes methods for the treatment of porous webs to controllably cause additives and/or modifiers to orient on and within: (a) a thin film of a polymer composition encapsulating the structural elements (i.e., the fibers or filaments) making up the web, leaving at least some of the interstitial spaces open; (b) an internal layer of a polymer composition between the upper and lower surfaces of the web; or (c) some combination of the foregoing. One of the many modifiers disclosed is iodine as a biocidal and antimicrobial agent. No data were provided regarding the effectiveness of this treatment.
U.S. Pat. No. 6,120,784 to Snyder, Jr., issued Sep. 19, 2000, discloses a method of imparting anti-pathogenic properties to a substrate material comprising: (a) preparing a coating composition containing an anti-pathogenic agent consisting essentially of PVP-I and N-9 in a ratio of from about 100:0 to about 0:100 of PVP-I to N-9, the coating composition further containing a pre-mix solution with which the anti-pathogenic agent is intimately mixed in a ratio of from about 6:4 to about 8:2 of agent to pre-mix on a dry basis, and having a percent solids content of from about 5% to about 35% solids; (b) feeding the anti-pathogenic coating composition into a coating machine; (c) loading substrate onto the coating machine; (d) operating the coating machine such that the coating composition comes into intimate contact with at least one surface of the substrate; and (e) drying the coated substrate material. Suitable substrates for use in conjunction with the anti-pathogenic formulation include paper, paper laminates, non-woven materials, non-woven laminates, and other similar substrates. The invention is primarily concerned with substrates targeted for use in medical-type applications, such as surgical gowns and drapes, examining table paper, hospital bed pads, hospital bed inserts and sheeting, surgical masks and other hospital or medical-type applications.
U.S. Pat. No. 6,228,128 to Johansen et al., issued May 8, 2001, discloses a method of antimicrobial treatment using a combination of a laccase enzyme and an enhancer capable of killing or inhibiting microorganisms, more specifically microorganisms present in laundry, on hard surfaces, on skin, teeth or mucous membranes; and for preserving food products, cosmetics, paints, coatings, etc., the composition comprising a laccase enzyme and an enhancing agent acting as an electron donor.
U.S. Pat. No. 6,251,386 to Johansen, issued Jun. 26, 2001, discloses an enzymatic composition capable of killing or inhibiting microbial cells or microorganisms, more specifically microbial cells or microorganisms present in laundry, on hard surfaces, in water systems, on skin, teeth or mucous membranes; and for preserving food products, cosmetics, paints, coatings, etc. The composition includes a haloperoxidase, a hydrogen peroxide source, a halide source, and an ammonium source, in particular an ammonium salt or an aminoalcohol, in which there is a hitherto unknown synergistic effect between the halide and the ammonium source.
U.S. Pat. No. 6,325,969 to Aamodt et al., issued Dec. 4, 2001, discloses a porous paper product impregnated with at least one chemical species. For example, paper impregnated with precursors of chlorine dioxide is disclosed. The chlorine dioxide suppresses the growth of bacteria. Other examples of antimicrobial agents include aqueous hydrogen peroxide, acetic acid, limonene in water, aqueous potassium sorbate and combinations thereof. These agents were tested by spraying them on paper. The tests measured the area in which growth of bacteria was prevented rather than the amount of bacteria killed.
All of the surveyed antimicrobial agents are intended to limit the growth of non-lethal bacteria and microorganisms such as mold and odoriferous growths which may be damaging but which are rarely life threatening. None of the known antimicrobial agents appears to be capable of killing anthrax bacteria on contact.